Clearing the System.Runtime.Caching.MemoryCache

In one of the applications I’m building I wanted to abstract away the usage of the .NET MemoryCache behind a nice clean interface:

	/// <summary>
	/// Implement this interface as an abstraction of a Cache implementation
	/// </summary>
	public interface ICache<K, V>
	{
	/// <summary>
	/// Get the object from the Cache
	/// </summary>
	/// <param name="key"></param>
	/// <returns></returns>
	V Get(K key);
	/// <summary>
	/// Put the object in the cache
	/// </summary>
	/// <param name="key"></param>
	/// <param name="value"></param>
	void Put(K key, V value);
	/// <summary>
	/// Remove an item from the Cache.
	/// </summary>
	/// <param name="key">The Key of the Item in the Cache to remove.</param>
	void Remove(K key);
	/// <summary>
	/// Clear the Cache
	/// </summary>
	void Clear();
	}

view raw ICache.cs hosted with ❤ by GitHub

Implementing most parts of this interface wasn’t hard but I struggled with the Clear method. There is no easy way to just clear all items from the MemoryCache. I tried the Trim() method but it had not the desired effect. I was able to solve it by disposing the existing cache instance and creating a new one behind the scenes. Here is the complete implementation:

	public class InMemoryCache:ICache<string,object>
	{
	private MemoryCache _cache;
	public InMemoryCache(string name="SampleCache")
	{
	_cache = new MemoryCache(name);
	}
	public object Get(string key)
	{
	return _cache[key];
	}
	public void Put(string key, object value)
	{
	_cache[key] = value;
	}
	public void Remove(string key)
	{
	_cache.Remove(key);
	}
	public void Clear()
	{
	var oldCache = _cache;
	_cache = new MemoryCache("SampleCache");
	oldCache.Dispose();
	}
	}

view raw InMemoryCache.cs hosted with ❤ by GitHub